Audio Research SP-10 preamplifier Page 2

Both preamps are nicely styled and have good basic features. The Audio Research SP-10, however, wins hands-down on ergonomics. You have switchable gain, a choice between two turntable inputs or Mute at the phono stage, and switchable cartridge loading. For most high-end audiophiles these are useful controls. The Conrad-Johnson combination has a slight advantage because its balance control is infinitely variable while the Audio Research control is stepped-and yes, dammit, there are times when the ARC's balance switch won't "lock in" at just the right place.

Both units are big and involve two rack-mountable boxes. The SP-10 has a separate preamp and power supply; the Conrad-Johnson a separate preamp and head amp. The ARC equipment is a muted silver grey with knobs that match the panel, and the C-J equipment is in burnished gold with gold knobs.

Both combinations seem to balance out in terms of the sonic impact of switches and wires. The SP-10 normally needs to be operated in the bypass mode to do its best, and even William Z. Johnson would probably admit that the variable loading and dual phono input switches impose a slight sonic degradation. I would also strongly advise getting the optional long umbilical cord between the SP-10 power supply and the SP-10 preamp, and using side-by-side rather than over-under placement to minimize hum. You also need to pay exceptional attention to grounding; for some reason the SP-10 is very sensitive to improper grounding, interconnect termination, and AC line-plug orientation.

I should also note that the SP-10 is sensitive to shock. The SP-10 is particularly sensitive in that its input tube—the 6DJ8—can become microphonic in use, or in transit. If you have noise problems, if there is more tube noise in one channel than the other, or if the highs sound slightly disembodied from the midrange on the SP-10, the chances are that changing a 6DJ8 will quickly cure the problem.

Both preamps have the precise "feel" of expensive equipment, and both provide excellent sound. They do, however, sound different in several important ways. The Audio Research SP-10 has the flat, extended upper octaves of the very best transistor equipment, plus all the virtues of tubes; no transistor lover will feel slighted to own the SP-10. Its variable loading also allows a quick approximate calibration of the best loading for a given cartridge.

The end result is that the SP-10 almost seduces you into lisening to upper midrange detail while loading a cartridge for the most precise imaging. Since the SP-10 is amazingly silent in its switching functions (even in Phono and with high gain), you may well start playing with the loading just to match an individual record. The outstanding merit of the SP-10 is in its top four octaves. You will hear more detail in a musically natural form in these octaves with the SP-10 than from any other preamp I've heard.

The Conrad-Johnson head amp and Premier Three, in contrast, do best in the three octaves above the bottom octave. They are strongest in the areas where tubes traditionally are strongest. You can, for example, hear the bowing sound on a violin more clearly than on an SP-10. Soundstage noises were clearer, because most occur in the frequency band where the C-J does best, and the C-J combination has superior imaging in terms of stability and centerfill.

The units differ in depth presentation. The ARC provides more upper-octave depth information. The C-J provids more bass and lower-midrange depth information. This slightly favors the C-J for orchestral music, because more hall depth-information seems to be present in the frequencies the C-J favors.

Let me hazard another description of the two units. The SP-10 is ideal in reproducing closely miked chamber music, female voice, natural jazz, and other music where you might choose to sit within 30 feet of the performers. The C-J combination is ideal for reproducing the larger orchestra or musical combination, and opera. Both reproduce all music very well, but the two units tend to place you in different parts of the concert hall. The SP-10 brings you close to the music. The C-J is twentieth row center.

Another way of putting it is that the ARC preamp is "fast" and the C-J is "sweet." A pejorative way of saying the same thing is that the ARC is "hard" and the C-J is "rolled-off." So much for semantics; the point is that they are audibly different, and you should pay close attention to their characteristics in making your choice.

I will ignore the issue of which is best; this is a matter of taste, and a choice you can make for yourself. They are as different in sound as fine wines from the same district. You may find that the C-J combination performs slightly better with cartridges that have extremely fast highs with a slight rise, while the SP-10 benefits from a cartridge that has flat frequency response.

Although both units performed without fault during my listening, they require care and sense. Shock and rough handling are no-nos. Mixing tubes to try to improve on the designer is a recipe for trouble both sonically and in terms of reliability. Cautious cleaning of the tube prongs with Tweek, according to the instructions that come with Tweek, can be recommended. Regular retubing at the manufacturer's recommended intervals is an unfortunate and expensive necessity.

The End Result
Both the Conrad-Johnson and Audio Research combinations provide a consistently more accurate reproduction of music, voice, and speech than any transistor unit I have heard in my own home. This accuracy shows up in several key areas, and is evident with a very wide range of source material and over a long period of time.

Both the Audio Research and Conrad-Johnson electronics are what the High End is all about. They are part of that elite group of equipment which leads the way towards filling the awkward gap between live performances and reproduced sound, and which allows you to explore nearly 100 years of recorded sound to its best potential. They, like virtually all high-end equipment, are luxuries and not cost-effective investments. While some of the best things in life may be free, none of them are cost-effective.—Anthony H. Cordesman

COMPANY INFO
Audio Research Corporation
3900 Annapolis Lane North
Plymouth, MN 55447-5447
(763) 577-9700
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